Internal combustion engines may have at least one cylinder head and a cylinder block which are connected to one another to form the individual cylinders or combustion chambers. The cylinder head often accommodates the valves controlling charge exchange, wherein each cylinder has one or more outlet openings or exhaust lines for the discharge of the exhaust gases via an exhaust-gas discharge system and has one or more inlet opening or intake lines for the supply of charge air via an intake system. On the intake side of an internal combustion engine, a charge-air cooler may be arranged in the intake system. The charge-air cooler may lower the temperature of the charge air and thus increase the density of the charge air. In this way, the cooler contributes to an increased charging of the combustion chamber. Supercharged internal combustion engines are often equipped with a charge-air cooler. Charge-air cooling arrangements may also be provided in naturally aspirated engines.
The cooling of the charge air via a charge-air cooler serves, in part, to increase the power of the internal combustion engine. The air used in the combustion process may be compressed as a result of the cooling, thus a greater mass of may be supplied to each cylinder per working cycle. In this way, the fuel mass and therefore the mean pressure may increase.
Furthermore, a reduction of the temperature of the cylinder fresh charge from charge-air cooling may reduce thermal loading of the internal combustion engine and a lower concentration of nitrogen oxides (NOx) in the exhaust gas thus reducing nitrogen oxide emissions.
In supercharged applied-ignition engine embodiments, auto-ignition may occur in the fuel-air mixture before the applied ignition is initiated, called knocking. These knocking events may be associated with high pressure gradients and intense noise generation, and may contribute to component degradation. Knocking may be counteracted by lowering the charge-air temperature, such that it may be possible and appropriate to dispense with conventional measures for preventing knocking, such as shifting the ignition time in the early direction. Thus, the disadvantages associated with the shift of the ignition time, specifically the resulting impairment of efficiency, may be reduced or eliminated.
Limiting the thermal loading of the internal combustion engine and/or preventing thermal overloading of individual engine components by lowering the temperature of the cylinder fresh charge, had been previously achieved using charge enrichment (λ<1). This is commonly performed so that both the temperatures in the combustion chamber and the exhaust-gas temperatures can be lowered. Here, more fuel is injected than can actually be burned with the provided quantity of air. Thus, the excess fuel is heated and evaporated, such that the temperature of the cylinder fresh charge falls as a result of internal cooling. However this approach results in increased fuel consumption and pollutant emission.
The inventors found that using a refrigerant evaporator cooler achieves a technical result of cooling charge air to prevent engine knock without reducing fuel efficiency. Further, air charge may be cooled prior to compression significantly decreasing the internal air charge pressure for increased engine power.
Thus, in an embodiment may include a supercharged engine having a cylinder head coupled to one or more cylinders. Each cylinder may have at least one outlet opening, coupled to an exhaust line for discharging the exhaust gases via an exhaust-gas discharge system. Each cylinder may have one or more inlet openings coupled to an intake line for supplying charge air via an intake system, wherein in the intake system may include at least one compressor for compressing the charge air and a charge-air cooler for cooling the charge air. The charge air cooler may be a refrigerant evaporator through which a refrigerant and the charge air can flow. Thus, the charge air may be cooled by at least partial evaporation of the refrigerant before entering the at least one compressor.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.